Final answer:
The criteria for solder include melting point, strength, conductivity, wetting properties, and compliance with industry standards like RoHS. Solder is commonly an alloy of tin and lead, with variations chosen based on application requirements.
Step-by-step explanation:
The criteria for solder in electronic engineering often involve considerations of its melting point, strength, conductivity, and the ease with which it can be used to create a strong, durable, and conductive bond between components.
Solder is typically an alloy of tin and lead, though lead-free alternatives are becoming more prevalent due to health and environmental concerns. For electronics, a common solder composition is a 60/40 tin-lead alloy, which has a melting point of about 188°C (370°F).
The ideal solder should also have good wetting properties, which allow it to flow over the surface of the materials being joined. Additionally, compliance with industry standards like RoHS (Restriction of Hazardous Substances) is also a key criterion for solders used in the manufacturing of electronic devices.
RoHS aims to limit the use of certain hazardous substances, including lead, in electrical and electronic equipment. Therefore, the selection of solder may also be guided by regulatory requirements.